Recent studies focused on amphibians highlight the significant ecological role of red-backed salamanders and emphasize that taking proactive steps can help avoid detrimental effects from a wildlife disease spreading in Europe, which has yet to reach North America.
Researchers have known that red-backed salamanders are plentiful in eastern North America, but a new study reveals that their populations and biomass in the region are much higher than previously realized. The study revealed an estimate of around 5,300 salamanders per forest area equivalent to a football field in the Northeast. Although each salamander is only about 3 inches long, their large numbers indicate that they contribute significantly to the overall biomass of non-insect animals in the Northeast, rivaling or even exceeding that of white-tailed deer.
The research titled “Range-wide Salamander Densities Reveal a Key Component of Terrestrial Vertebrate Biomass in Eastern North American Forests,” conducted by the U.S. Geological Survey alongside various partners, marks the first comprehensive calculation of the densities and biomass of this common yet seldom seen species across its natural habitat.
The significant presence of red-backed salamanders in the Northeast uncovered by this research suggests that these amphibians, and possibly amphibians in general, may hold a more substantial role in terrestrial temperate ecosystems than was previously understood.
As Evan Grant, the lead author and a research wildlife biologist at USGS, noted, “The substantial biomass of red-backed salamanders indicates that they are likely ‘small but mighty’ in their contribution to the ecological balance of northeastern forests. Their absence could lead to considerable ecosystem-level repercussions.”
Many salamanders, including the red-backed variety, are small and tend to stay underground most of the time, making them easy for people to overlook. Grant often describes them as “hidden biodiversity,” because even though they are frequently plentiful, they remain elusive. However, their ecological functions are crucial. Salamanders consume organisms that are too small for larger predators, and they themselves are prey for various animals, thus playing an essential role in the food web of their ecosystem.
“Salamanders are essential to forest ecosystems,” says David Miller, a professor of wildlife ecology at Penn State and co-author of the study. “They play a crucial role at the top of the food chain on the forest floor, where organic matter decomposes and nourishes the entire web of life. Given their importance, we can use them as indicators of forest health.”
Unfortunately, just as researchers are starting to grasp the significant “hidden biodiversity” and vital ecological functions of salamanders, a troubling new wildlife disease poses a serious threat to them and raises concerns among scientists and wildlife managers.
Batrachochytrium salamandrivorans, known as Bsal, is a fungal disease related to the chytrid fungus that has already wreaked havoc on amphibian populations globally. First identified in the Netherlands in 2013, Bsal has devastated salamander populations in central Europe and continues to spread throughout the continent.
As of now, Bsal has not been found in the United States, prompting scientists and wildlife managers to get ready for its potential arrival. A North American Bsal Task Force has been established with the aim of minimizing the spread and impact of Bsal in North America. However, resource managers faced challenges in implementing proactive management measures for a disease that has not yet appeared on U.S. soil.
They needed to present evidence that proactive management would be more effective than merely reacting once Bsal is discovered. To address this, Grant co-authored another recent study which explored various proactive and reactive management strategies to predict their long-term effects on salamander populations.
This investigation titled “Proactive management outperforms reactive actions for wildlife disease control” utilized computer models to demonstrate what seems intuitively obvious: initiating management efforts before Bsal arrives is more effective in preserving salamander populations than responding after the disease appears or taking no action at all.
“If we remain inactive regarding Bsal, our model predicts that the impact on North American salamander species would be catastrophic,” said Molly Bletz, assistant professor of disease ecology at Penn State and the lead author of the second study. “This study strongly supports proactive management strategies. Essentially, if we want to ensure the survival of at-risk salamander species in the future, taking proactive steps is our best option.”
The proactive management strategies considered in the study include:
- Implementing barriers or enhancing habitat complexity to prevent amphibians from spreading the disease among themselves;
- Reducing the presence of Bsal fungal spores in aquatic environments by temporarily raising water temperatures, increasing salinity, or boosting the abundance of zooplankton that consume fungi;
- Helping amphibians combat the disease by improving their health through supplemental feeding, increasing local beneficial anti-fungal microbes, or by vaccination.
While this second study did not assess the potential effects of proactive management for Bsal on the wider ecosystem, visitor satisfaction, or financial implications, Bletz, Grant, and their colleagues are already working to evaluate these aspects to provide managers with a comprehensive view of the benefits of proactive versus reactive management approaches.
“Understanding the incredibly significant role of salamanders in our ecosystems, combined with strong evidence supporting the advantages of proactive management for salamander populations threatened by Bsal, makes it more crucial than ever to protect the ‘hidden biodiversity’ of amphibians,” concluded Bletz.
